The studies proposed here deal with the development of optimal screening strategies for cervical neoplastic disease and adenocarcinoma of the endometrium and their precursor lesions. A clinical and histologic construct is provided as a theoretical model of the natural history of these neoplastic diseases. With this model, using available data from such sources as the Third National Cancer Survey and standard methods of statistical analysis, methods of evaluating the effects of different screening strategies on the indices of incidence, survival and mortality in the population at large or in selected subsets at differential risk will be developed. Screening for cervix lesions on an annual basis was instituted empirically. Changes in the interval between successive examinations have been suggested based on estimates of the differential risk of incidence. The results of such changes in screening together with methods to optimize screening on a cost for case ascertainment basis will be examined. There is evidence that there is an increasing incidence of endometrial cancer in the United States. Screening for endometrial lesions in the population is not done routinely although methods are available for ascertaining endometrial pathology. The identification of groups with differential risk of incidence of endometrial lesions together with estimates to quantify this increased risk will be presented and the costs involved for screening on a selective basis studied. A study of measures of association used as indices of the relationship between the incidence of a given lesion and other traits will be done. The index of relative risk is used in the characterizing of subsets in the population for which selective screening may be justified. An investigation of statistical methods for obtaining an estimate of this index in the presence of more than one risk factor will be carried out.